import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.Scanner;

public class Q2 {
	public static void main(String[] args) throws Exception {
		BufferedWriter fileout = new BufferedWriter(new FileWriter("OUT2.txt"));
		Scanner scan = new Scanner(new FileReader("DATA2.txt"));
		int[] primes = new int[50000];
		primes[0] = 2;
		primes[1] = 3;
		primes[2] = 5;
		primes[3] = 7;
		int i2 = 4;
		for (int current = 3; current < 100000; current += 2) {
			int i = 1;
			boolean prime = true;
			for (; i < primes.length; i++) {
				if (primes[i] == 0) break;
				if (current % primes[i] == 0) {
					prime = false;
					break;
				}
			}
			if (primes[i] == 0) {
				for (int i3 = primes[i - 1]; i3 < current; i3 += 2) {
					if (current % i3 == 0) {
						prime = false;
						break;
					}
				}
				if (prime) primes[i2++] = current;
			} else if (prime) {
				primes[i2++] = current;
			}
		}
		while (scan.hasNextInt()) {
			int max = scan.nextInt();
			int answer = 0;
			for (int i = 0; primes[i] > 0 && primes[i] <= max; i++) {
				answer += primes[i];
			}
			fileout.write("" + answer);
			fileout.newLine();
		}
		fileout.close();
	}
}